How to Setup DM-Multipath on RHEL & CentOS

Overview:

DM-Multipath stands for Device mapper multipathing. It allows us to configure multiple I/O paths between server and storage arrays into asingle device. These I/O paths are physical SAN connections that can include separate cables, switches, and controllers.

Multipathing aggregates the I/O paths, creating a new device that consists of the aggregated paths and remove the Single Point of Failure Problem.

Why To Use Multipathing :

Below are the two reasons why we are using DM-Multipath on Linux Servers :

Redundancy : In Case of active/passive multipathing we will be using two paths. One path will be used for I/O operations and other will be in stand by. If any element of an I/O path (like cable, switch, or controller) fails, DM-Multipath switches to an alternate path or stand by path.

High Performance : In case of active/active multipathing , I/O operations are shared over available paths in round-robin fashion and provide improved performance.

Installation of DM-Multipath on RHEL / CentOS

‘device-mapper-multipath’ is the multipath rpm package

# rpm -q device-mapper-multipath

if it is not installed then use the below yum command :

# yum install device-mapper-multipath

Setting up multipathing :

‘/etc/multipath.conf’ is the default configuration file for multipathing , if this file doesn’t exists , copy the sample file :

2 comments

sir,
Ur explanation is very good about multipath. i have a small doubt. my external usb hard disk is also detecting under multiptah. how to black list my external usb hard disk like my local disk. please help me.